A slide fastener is widely used in openings of bags or the like to open/close them. As the slide fastener, a both-open type slide fastener in which two sliders are disposed at a pair of fastener stringers for head fitting or tail fitting or a one-open type slide fastener in which one slider is disposed has been known.
In the both-open type slide fastener, the slide fastener can be opened/closed even by sliding two sliders in any direction of forward and backward directions along the tooth line. Further, in the one-open type slide fastener, the slide fastener can be opened/closed by sliding the slider.
As a tooth that is attached to slide fasteners such as the both-open type slide fastener or the one-open type slide fastener, there is a matter using a metal double-sided tooth. It is possible to achieve a slide fastener that is strong against horizontal pulling strength, has a metal shiny surface, and has excellent external appearance by using the metal double-sided tooth. For the shape of the metal double-sided tooth, a coupling convex portion and a coupling concave portion are all formed on both sides of the coupling head. The coupling convex portion that is formed on a counterpart side for coupling may be coupled to the coupling concave portion.
As an example of the metal double-sided tooth, the present applicant(s) has proposed a tooth of a slide fastener configured by a metal double-sided tooth formed by forming (see Patent Document 1). FIG. 9 illustrates a perspective view of a metal double-sided tooth described in Patent Document 1, as an example of the related art in the invention. As illustrated in FIG. 9, a metal double-sided tooth 50 includes a coupling head 51, a body 52 disposed at the rear end of the coupling head 51, and a pair of left and right legs 53 extending from the rear end of the body 52.
The coupling head 51 has a thin flat plate portion 57, a pair of coupling protruding portions 54, a pair of left and right side protruding portions 55, and a pair of coupling concave portions 56. The thin flat plate portions 57 are formed at the center portions of both front and rear sides of the body 52 and are formed to be thinner than the plate thickness of the body 52. The pair of coupling protruding portions 54 protrudes from both of front and rear sides at the left and right center portions of the thin flat plate portion 57.
The pair of left and right side protruding portions 55 extend from the thin flat plate portions 57 disposed at the left and right of the coupling convex portions 54 toward both of the front and rear sides of the body 52, and are integrally formed with the body 52. Further, the pair of coupling concave portions 56 is formed as the region surrounded by the coupling convex portions 54, the side protruding portions 55, and the body 52. The coupling convex portion 54 that is a counterpart for coupling may be coupled to the coupling concave portion 56.